Mario vs Charizard originated as a fanmade DEATH BATTLE that was created by the user known as "Mario9987" on November 7th 2015. The meme is a copypasta from the battle page with the battle because of it's absurdity. The actual fight (excluding the meeting and the victor leaving the battle scene) is only 4 lines long and it goes as follows:
Charizard ran towards Mario and used bite.
Mario laughed and kick Charizard in the balls.
Charizard fell down .
Then Mario picked him up and snapped his neck
The battle was short due to the writer having to go to school and many users who read it complained that it was short or that it was bad. The battle became a meme sometime during June of 2016 when Dio the Ludicolo posted the battle in the chat. Since then this battle has been used as a copypasta in the chat at random moments usually having a month seperating the uses.